Exception block static analyzer tool (RavenDB-3879)

[ElemarJR]

Hello there,

This PR addresses the following scenarios:

empty catch blocks will generate a diagnostic asking for a properly implementation or comment

            try
            {
                // do something
            }
            catch (Exception ex)
            {
            }

catch blocks with just logging (followed or not with a return or break statement) will generate a diagnostic asking for a comment

try
            {
                // do something
            }
            catch (Exception ex)
            {
                log.Error(""bla bla"", ex);
            }

"try if not null dispose pattern" will not generate any diagnostic

            try
            {
                foo.Dispose();
            }
            catch {}

            try
            {
                if (foo != null) foo.Dispose();
            }
            catch {}

catch blocks with ToDo Comments (TODO, HACK, UNDONE, FIXME) generates a diagnostic reporting this as a problem

            try
            {
                // do something
            }
            catch (Exception ex)
            {
                log.Error(""This was an error"", ex); 
                // TODO: I should write a good comment here
            }

This is it.